Experimental study on internal one-dimensional heat conduction law of granite under high-temperature thermal shock

The deteriorating effects of heat on physical and mechanical properties of rock are determined by the combination of the factors such as the structure, mineral composition and mineral distribution of the rock. The high-temperature thermal shock tests are conducted to address the one-dimensional heat conduction problem of semi-infinite objects experiencing high-temperature thermal shock in engineering. The changes rules of temperature field, heating rate and temperature gradient field during thermal shock are analyzed, the thermal shock factor is introduced to quantitatively characterize the degree of heat damage to the rock in the process of high-temperature thermal shock, and the influence of heat source temperature and medium on the heat transfer of granite are discussed. The test results show that the temperature changes within the granite at different thermal shock temperatures are divided identically into three stages: rapid heating, slow heating and temperature stabilization. Influenced by the non-homogeneity of granite, the distribution of the temperature field and temperature gradient field in granite under high-temperature thermal shock are disordered, and the degree of disorder of the temperature gradient field is higher than that of the temperature field. During high-temperature thermal shock, the distribution of thermal shock factors of granite is significantly non-homogeneous, and its peaks are dynamically moving. At 100℃, since water has a greater convective heat transfer coefficient than silicone oil, the temperature, rate of warming and temperature gradient within the granite have greater peaks and enter the stabilization phase earlier when using water instead of silicone oil as the heat source medium.